Abstract : A system for mooring a buoyant case such as a marine mine or other marine device at a preselected depth below the surface of the water in which the case was launched. After the case has been launched, and made bottom contact, the mooring system utilizes a first piston assembly in conjunction with a corrodible pin to initiate mooring line payout from a buoyant case to an attached anchor. When the preselected mooring depth is reached, a second piston assembly terminates the mooring line payout and the ascent of the case, thereby resulting in mooring of the buoyant case at the preselected depth. (Author)